The research projects proposed here are closely interrelated and have been evoked from past research productivity and collaboration. The common aim of the five research units is to expand our knowledge in the neuroendocrine control of reproductive function in humans. Animal experimentations will be conducted for those studies which are not feasible with human subjects such as synthesis, processing and secretion of GnRH and GnRH-related peptides (Sarkar, Unit 3) and the role of POMC peptides in the regulation of reproduction (Rasmussen, Unit 4). Cellular and biochemical mechanisms will be explored through the use of a variety of in vitro techniques, in which both animal and human tissues and cells will be employed. The strategy for the investigation in humans is to circumvent the inherent limitations placed on the kind of experimental procedures by selecting disease states to serve as "nature made" experiments and represent important complements to the physiological studies in humans and the laboratory based "man-made" experiments in animals. Studies of neuroendocrine control of the human menstrual cycle continue to be a major focus of this proposal; aberrations of the link between the brain and ovary in several disease states will be explored; luteal phase defects, polycystic ovary syndrome, anorexia-bulimia and psychogenic amenorrhea (Yen, Unit 1) as well as the psychoneuroendocrine basis of premenstrual syndrome (Mortola, Unit 2). Finally, the postpartum hypothalamic amenorrhea model, by virture of the associated GnRH deficiency and its spontaneous recovery, will be utilized to investigate hypothalamic GnRH secretion (Liu, Unit 5). The participants in this proposed research have been selected not only because of their conjoint interests in the neuroendocrine control of reproductive processes but also because their past performance of collaboration on research projects.